Pneumatic disk brake with pressure elements

ABSTRACT

A disk brake, preferably a compressed air operated disk brake, comprising a caliper which encompasses the brake disk, and an actuating device which is arranged on one side of the brake disk and provided with a pivotally mounted rotary lever. The rotary lever acts upon a cross member which can be displaced in relation to the disk brake on an eccentric device provided with a pressure element. The invention is characterized in that the at least one pressure element of the eccentric device forms a spherical element.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of PCT internationalapplication no. PCT/EP01/03814, filed Apr. 4, 2001, and claims prioritybased on German patent application no. DE 100 21 571.8 filed May 3,2000, the specifications of which are incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

[0002] The invention relates to a disk brake, preferably a compressedair (pneumatic) operated disk brake, comprising a caliper whichencompasses the brake disk, and an actuating device which features arotary lever supported on pivot bearings. The actuating device isarranged on one side of the brake disk. The rotary lever rests againstan eccentric device featuring a pressure element and acts directly orindirectly upon a cross member, which can be displaced in relation tothe brake disk.

[0003] In generic disk brakes, the transmission of forces occurs whenthe brake cylinder is operated through a rod, which acts upon the rotarylever. The rotary lever is supported in the caliper housing by means ofa pivot bearing. A cylindrical pivot-bearing shaft of an eccentricdevice is arranged in a recess in the rotary lever offset against theaxis of rotation. Pivoting of the rotary lever causes a spring-loadedcross member to be displaced transversely relative to the surface of thebrake disk. On the side facing away from the brake disk, this crossmember engages at least one rotary spindle with a pressure plate, whichpresses against the brake shoe when the brake is operated, so that thebrake lining contacts the brake disk. The generic disk brake can beexecuted as a single-spindle device or as a double-spindle device.

[0004] In known disk brakes, the moveable components, particularly thesupport of the eccentric device and the rotary lever against thehousing, are to some extent executed as maintenance-free plain bearinghalf liners or as roller bearings. The rotary lever is supported insemi-cylindrical plain bearing half liners in the area of the housingfacing away from the brake disk. The eccentric bearing is supportedeccentrically to the bearing of the rotary lever in a semi-cylindricalrecess in the rotary lever. A roller bearing in the form of asemi-cylindrical liner is inserted into this recess. Force istransmitted through the cylindrical shaft.

[0005] When the disk brake is operated, transverse forces develop due tothe diagonal running of the bearings, which is caused by tolerances andby deformations linked to operating conditions, as well as by thevibration stress occurring during vehicle operation and the resultingforces of gravity. Consequently, corresponding locking elements for therotary lever and for the cylindrical pressure elements arranged in theball cups are needed to transmit the transverse forces. In addition,mechanically tooled guide surfaces are also necessary. The guidesurfaces and locking elements not only increase production costs, butalso increase the complexity of assembly of the disk brake. In addition,susceptibility to failure is increased.

[0006] Consequently, the underlying problem behind the invention is todesign a compressed air operated disk brake using a simple design, sothat the transverse forces occurring upon operation of the brake can betransmitted without locking elements and without guide surfaces. Inaddition, the disk brake should continue to exhibit high stability underload and should be designed in compact form.

[0007] This problem is solved by providing a disk brake wherein at leastone pressure element of the eccentric device is designed to beessentially spherical or oval-, and/or barrel- or bale-shaped, thuscomprising a spherical pressure element.

[0008] The transverse forces occurring during the braking process arenow no longer removed by means of additional locking elements and theguide surfaces that are necessary as a result, but rather through thespherical pressure elements themselves. Consequently, the design can bemanufactured in an especially cost-efficient manner, due to thereduction in the number of components, and, furthermore, is easilyassembled. As the number of components is reduced in comparison to knowndesigns, susceptibility to failure is reduced.

[0009] An especially advantageous embodiment of the invention ischaracterized by the fact that the spherical pressure elements aresupported in essentially dome-shaped plain bearing half liners, which,in a structurally simple manner, interact with the spherical pressureelements to absorb the transverse forces that occur. The sphericalpressure elements or their plain bearing half liners can be insertedinto essentially dome-shaped recesses in the bridge or cross member andthe rotary lever or in the caliper and the rotary lever.

[0010] Various embodiments of the invention can be formed. According toa first exemplary embodiment, the bridge acts upon a single rotaryspindle with a pressure plate essentially centered in the bridge,wherein the cross member runs at an angle to the rotary spindle and issupported on the rotary lever by one of the spherical pressure elementson each side of the rotary spindle.

[0011] Alternatively, it is contemplated that the cross member acts upona single rotary spindle essentially centered in the bridge, wherein thebridge runs on both sides of the pressure element and engages the rotarylever, which is supported by the spherical pressure elements on thecaliper.

[0012] In addition to the single-spindle embodiments, correspondingdouble-spindle designs can also be used. Thus, for example, it isadvantageous if the cross member acts upon two pressure plates and/orrotary spindles arranged in parallel to one another, wherein the crossmember is supported by at least two of the spherical pressure elementson the rotary lever. Alternatively, the cross member acts upon twopressure plates and/or rotary spindles arranged in parallel to oneanother, wherein the cross member contacts the rotary lever through apivot bearing, which is supported by at least one of the sphericalpressure elements on the caliper.

[0013] The plain bearings are easily fixed in place by attaching ormolding at least one peg or protrusion, to secure against torsion, tothe sides of each of the dome-shaped plain bearing half liners facingthe recesses, with the peg or protrusion engaging a correspondinglyshaped pocket hole in the bridge/cross member or the part of the caliperor the rotary lever facing away from the brake disk.

[0014] The protrusion can also be designed to accept a lubricant, aseither a hollow peg or hollow protrusion, which is open to the bearingsurface of the ball cup.

[0015] As the number of components is reduced in comparison to knowndesigns, the invention also reduces susceptibility to failure. Normally,it is not necessary to feature all plain bearing half liners as ballcups. Rather it is sufficient to feature at least one plain bearing halfliner in this form. In another embodiment, it is provided that at leastone of the spherical pressure elements is inserted with a positive fitinto the corresponding ball cup, while the remaining roller bearings aremoveably inserted into the dome-shaped plain bearing half liners. Thisguarantees axial locking. However, tolerances and deformations linked tooperating conditions can be absorbed in the corresponding components, asthere is a predetermined and limited mobility of the components insertedin the dome-shaped plain bearing half liner. The dome-shaped plainbearing half liners are advantageously oval-shaped for moveableacceptance of the eccentric device and/or the roller bearings. However,there is relatively little play.

[0016] The spherical pressure elements can be cost-efficiently designedas roller bearings, which are commercially available from relevantmanufacturers. They generally provide extremely high surface quality, asthe maximum peak-to-valley height is two one-thousandths of a millimeter(0.002 mm). The dome-shaped plain bearing half liners are preferablymanufactured from a suitable, highly stress-resistant, plain bearinghalf liner material (e.g., a composite bearing with polymer slidingcoating). Alternatively, the dome-shaped plain bearing half liner canalso be made of graphite.

[0017] Alternatively, a suitable plain bearing material can be applieddirectly to the surface of the dome-shaped liner for acceptance of theball, e.g., in the form of a sliding sheet.

[0018] Other objects, advantages and novel features of the presentinvention will become apparent from the following detailed descriptionof the invention when considered in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a cross-sectional view of a pneumatically operated diskbrake according to the invention in a first section.

[0020]FIG. 2 depicts the pneumatically operated disk brake according tothe invention shown in FIG. 1 in a sectional view rotated by 90°relative to FIG. 1;

[0021]FIG. 3 is a cross-sectional view of another pneumatically operateddisk brake according to the invention; and

[0022]FIG. 4 depicts the pneumatically operated disk brake according tothe invention shown in FIG. 3 in a sectional view rotated by 90°relative to FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS

[0023] The compressed-air disk brake 1 depicted in FIG. 1 is providedwith a brake disk 2 that is contacted by the brake lining 3 uponoperation of the disk brake, with said lining being secured to a brakeshoe 4. Operation of the brake shoe 4 occurs through an actuating device5, which is arranged in a caliper housing. The actuating device 5essentially consists of a cross member (or, more preferably in thiscase, a bridge) 7 displaceable at an angle to the brake shoe, a rotarylever 8 supported on pivot bearings, and an eccentric device (including,among other components, pressure element 9), which is arrangedeccentrically to the axis of rotation of the lower eccentric segment ofthe rotary lever 8.

[0024] In a manner not depicted here, an operating rod engages the endof the rotary lever 8 opposite the axis of rotation of the rotary lever,so that the rotary lever 8 is pivoted in a counter-clockwise directionupon operation of the disk brake 1, as is depicted in FIG. 1. As aresult, the bridge 7 is displaced against the action of pressure springs10 in the direction of the brake shoe 3, so that tensing of the diskbrake 1 is achieved. The pressure springs 10 release the braking effectas soon as the braking process has ended. In the embodiment depicted inFIG. 1, the rotary lever 8 is supported on the caliper via aroller-pivot bearing 11 (see FIG. 2). In this embodiment, theroller-pivot bearing 11 rests against the side of the rotary lever 8facing away from the brake shoe 4.

[0025] The design of the rotary lever 8 is essentially T-shaped, whereinthe section of the rotary lever 8 facing the eccentric device featurestwo essentially semi-spherical, dome-shaped recesses into which twospherical pressure elements in the form of roller bearing balls 9 (thatare part of the eccentric device) are inserted for purposes of powertransmission. Also provided, as depicted in FIG. 1, are two properlyaligned, dome-shaped recesses, into each of which a dome-shaped plainbearing half liner 12 is inserted. The dome-shaped plain bearing halfliners 12 are made of a wear-resisting plain bearing half linermaterial.

[0026] In the embodiment depicted in FIGS. 1 and 2, a hollow cylindricalprotrusion 13 (peg), which is essentially conically shaped at its freeend, is molded onto the side of the ball liner 12 facing away from theroller bearing ball 9. For the purpose of permanent lubrication of theball liner 12, a lubricant, such as lubricating grease, can be filledinto the protrusion 13.

[0027] The embodiment depicted in FIGS. 1 and 2 is designed as asingle-spindle embodiment, as it is provided with only one settingspindle 15 and pressure plate 14. The disk brake 1 depicted in FIG. 1 isdesigned for utility vehicles having a low load range, and itsdimensions are correspondingly small. In contrast to the embodimentshown in the figure, the disk brake could also be executed as adouble-spindle disk brake, in which case two pressure plates 14 engagethe brake shoe 4.

[0028] In the embodiment depicted in FIGS. 3 and 4, the pivot bearing 11is arranged between the rotary lever 8 and the bridge 7. In contrast tothe depiction according to FIGS. 1 and 2, the roller-pivot bearings 9 ofthe eccentric device are arranged in recesses in the rotary lever 8 onthe side facing away from the brake disk 2. The dome-shaped plainbearing half liners 12 are again inserted into these recesses in therotary lever 8. The roller-pivot bearings 9 are in this case supportedby correspondingly designed, dome-shaped recesses in the caliper 6,which are shaped on the inside of the caliper (see FIG. 4). In contrastto the depiction, the dome-shaped plain bearing half liners 12 couldalso be inserted into grooves in the caliper 6.

[0029] The invention is not limited to the exemplary embodimentsdepicted. It is important, however, that at least one ball liner 12completely encompass the roller-pivot bearing 9 arranged inside it, soas to transmit the transverse forces during the braking process. Theremaining dome-shaped plain bearing half liners 12 could be designed insuch a way as to allow the rolling-pivot bearings 9 to be slightlydisplaced therein.

[0030] The foregoing disclosure has been set forth merely to illustratethe invention and is not intended to be limiting. Since modifications ofthe disclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

[0031] Table of reference numbers

[0032]1 Disk brake

[0033]2 Brake disk

[0034]3 Brake lining

[0035]4 Brake shoe

[0036]5 Actuating device

[0037]6 Caliper

[0038]7 Cross member (Bridge)

[0039]8 Rotary lever

[0040]9 Pressure element

[0041]10 Pressure spring

[0042]11 Roller-Pivot bearing

[0043]12 Plain bearing half liner—ball liner

[0044]13 Protrusion

[0045]14 Pressure plate

[0046]15 Rotary spindle

[0047]16 Pin

What is claimed Is:
 1. A disk brake, comprising: a caliper engageableabout a brake disk; an actuating device arranged in the caliper on oneside of the brake disk, the actuating device comprising at least arotary lever supported on pivot bearings and an eccentric device thatincludes at least one spherical pressure element having at least one ofan essentially spherical, oval, barrel and bale shape; and wherein thespherical pressure element is supported in an essentially dome-shapedplain bearing half liner.
 2. A disk brake according to claim 1, whereinthe eccentric device includes two spherical pressure elements supportedin essentially dome-shaped plain bearing half liners, and wherein theplain bearing half liners are inserted into corresponding dome-shapedrecesses arranged in: (a) a cross member and the rotary lever of theactuating device; or (b) a portion of the caliper away from the brakedisk and the rotary lever.
 3. The disk brake according to claim 2,wherein the actuating device includes the cross member carrying a singlespindle substantially centered therein, wherein the cross member extendstransversely with respect to the spindle and is supported on the rotarylever by one of the spherical pressure elements arranged on each side ofthe spindle.
 4. The disk brake according to claim 2, wherein theactuating device includes a cross member carrying a single spindlearranged substantially centrally therein, and wherein the cross memberextends transversely with respect to the spindle and engages the rotarylever, the rotary lever being supported by the spherical pressureelements on the portion of the caliper.
 5. The disk brake according toclaim 2, wherein the actuating device includes a cross member carryingtwo spindles arranged in parallel to one another, the cross member beingsupported by at least two of the spherical pressure elements on therotary lever.
 6. The disk brake according to claim 2, wherein theactuating device includes a cross member carrying two spindles arrangedin parallel to one another, the cross member contacting the rotary leverthrough the pivot bearing, and wherein the rotary lever is supported byat least one of the spherical pressure elements on the portion of thecaliper.
 7. The disk brake according to claim 1, wherein at least twospherical pressure elements are supported in corresponding dome-shapedplain bearing half liners, and wherein one of the liners encompasses oneof the spherical pressure elements with an essentially positive fit in aplay free manner, and wherein the other spherical pressure element isdesigned to be inserted into the liner while allowing for a limitedamount of movement.
 8. The disk brake according to claim 3, wherein atleast two spherical pressure elements are supported in correspondingdome-shaped plain bearing half liners, and wherein one of the linersencompasses one of the spherical pressure elements with an essentiallypositive fit in a play free manner, and wherein the other sphericalpressure element is designed to be inserted into the liner whileallowing for a limited amount of movement.
 9. The disk brake accordingto claim 4, wherein at least two spherical pressure elements aresupported in corresponding dome-shaped plain bearing half liners, andwherein one of the liners encompasses one of the spherical pressureelements with an essentially positive fit in a play free manner, andwherein the other spherical pressure element is designed to be insertedinto the liner while allowing for a limited amount of movement.
 10. Thedisk brake according to claim 5, wherein at least two spherical pressureelements are supported in corresponding dome-shaped plain bearing halfliners, and wherein one of the liners encompasses one of the sphericalpressure elements with an essentially positive fit in a play freemanner, and wherein the other spherical pressure element is designed tobe inserted into the liner while allowing for a limited amount ofmovement.
 11. The disk brake according to claim 6, wherein at least twospherical pressure elements are supported in corresponding dome-shapedplain bearing half liners, and wherein one of the liners encompasses oneof the spherical pressure elements with an essentially positive fit in aplay free manner, and wherein the other spherical pressure element isdesigned to be inserted into the liner while allowing for a limitedamount of movement.
 12. The disk brake according to claim 1, wherein theplain bearing half liner has an oval shape for moveable acceptance ofthe spherical pressure element.
 13. The disk brake according to claim 1,wherein the spherical pressure element is a roller bearing ball.
 14. Thedisk brake according to claim 13, wherein a surface of the rollerbearing ball has a peak-to-valley tolerance height of less than two onethousandths of a millimeter.
 15. The disk brake according to claim 1,wherein the dome-shaped plain bearing half liner includes at least oneprotrusion arranged on the liner so as to face a corresponding recess,the protrusion being engageable in a corresponding hole arranged in oneof a cross member, a portion of the caliper, or the rotary lever. 16.The disk brake according to claim 15, wherein the protrusion is hollowin order to accept a lubricant, one end of the protrusion being opentoward a bearing surface of the liner.
 17. The disk brake according toclaim 1, wherein the rotary lever acts directly or indirectly upon across member displaceable transversely with respect to the brake disk.